Application and evaluation of colloidal gold immunochromatography and modified carbapenem inactivation method combined with EDTA-carbapenem inactivation method in detection of bacterial carbapenemase

Objective To evaluate the clinical application of colloidal gold immunochromatography and modified carbapenem inactivation method (mCIM) combined with Ethylene Diamine Tetraacetic Acid (EDTA) carbapenem inactivation method (eCIM) in the detection of carbapenemase in common gram-negative bacteria.

Methods A total of 153 strains of carbapenem insensitive gram-negative bacteria were screened by mCIM combined with eCIM and colloidal gold immunochromatography. Using high-throughput sequencing results as the gold standard, the sensitivity, specificity, detection time and carbapenemase type identification power of the two methods were compared.

Results In 153 gram-negative bacteria which were insensitive to carbapenems, 121 carried carbapenemase gene indicated by high-throughput sequencing and drug resistance gene screening. In mCIM combined with eCIM, the sensitivity, specificity, positive prediction value and negative predictive value were 92.00%, 100.00%, 100.00% and 84.21%, respectively, in the detection of carbapenemase in Enterobacteriaceae, 73.91%, 100.00%, 100.00% and 84.21%, respectively, in the detection of carbapenemase in Acinetobacter baumannii and 95.65%, 100.00%, 100.00% and 96.97%, respectively, in the detection of carbapenemase in Pseudomonas aeruginosa. Compared with colloidal gold immunochromatography, mCIM combined with eCIM showed no significant differences in the detection of carbapenemase in P. aeruginosa (Fisher's exact test, P=0.999), but showed significant differences in the coincidence rate of carbapenemase detection in Enterobacteriaceae ( Fisher's exact test, P=0.029) and A. baumannii (Fisher's exact test, P=0.024). The detection time of colloidal gold immunochromatography was shorter than that of mCIM combined with eCIM, and the performance in carbapenemase type identification was better than mCIM combined with eCIM, but the cost was higher compared with mCIM combined with eCIM.

Conclusion There was no significant difference in the detection of carbapenemase in P. aeruginosa between the two methods. In the detection of carbapenemase in Enterobacteriaceae and A. baumannii, colloidal gold immunochromatography was more sensitive. Microbiology laboratories at different levels can select carbapenemase detection method according to the local carbapenemase type characteristics and specific conditions of patients.